Induction heating pressure welding with rotary bus bar joint

ABSTRACT

A method and apparatus is disclosed for induction heating weldable surfaces and moving the heated surfaces together with sufficient force to upset the surfaces while in a substantially inert atmosphere for thereby welding the surfaces together. The apparatus includes a rotary bus bar joint for moving the induction coil between the weldable surfaces, and also includes a clamping mechanism for handling members having weldable surfaces of different sizes and shapes. A pair of separately controlled induction coils may be used with or without laminations for heating tubular or solid members to an upsetting temperature.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention relates to the inventions described in thefollowing applications all of which are assigned to the assignee of thepresent invention, and are incorporated by reference herein.

Brolin U.S. application Ser. No. 844,656 filed on Mar. 27, 1986 entitledInduction Heating Pressure Welding.

Brolin U.S. application Ser. No. 902,858 filed on Sept. 02, 1986entitled Induction Heating With Adjustable Linear Bus Bar.

Brolin et al U.S. application Ser. No. 895,085 filed on Aug. 11, 1986entitled Inert Atmosphere Control For Induction Heating Pressure WeldingSystem.

Brolin et al U.S. application Ser. No. 896,904 filed on Aug. 11, 1986entitled Dual Induction Heat Pressure Welding Control Circuit.

BACKGROUND OF THE INVENTION Field of the Invention

The present invnetion relates to welding and more specifically relatesto welding metal members together by induction heating weldable surfacesof each member to upsetting or welding temperature and immediatelythereafter forcing the surfaces together with sufficient force to upsetthe weldable surfaces and weld them together.

SUMMARY OF THE INVENTION

The welding method and apparatus of the present invention comprises anapparatus which performs the steps of firmly clamping two members withtheir weldable surfaces spaced apart a sufficient distance to provide agap therebetween of sufficient size to receive at least one inductioncoil and air gaps therebetween. A substantially oxygen free inertatmosphere is formed around the weldable surfaces and induction coil andare then subjected to a high frequency current which heats the weldablesurfaces. Immediately thereafter the induction coil is moved away fromthe weldable surfaces and the two members are forced together withsufficient force to upset the heated surfaces and weld them together.The weldable surfaces are preferably of a fine finish.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective of major components of the inductionwelding apparatus of the present invention, certain parts being brokenaway and other parts being shown in section.

FIG. 1A is a central vertical section of two members welded togetherwith an inflatable air plug in one member.

FIG. 2 is a front elevation of the induction welding apparatus, certainparts being cut away.

FIG. 3 is a top plan of the induction welding apparatus, certain partsbeing cut away.

FIG. 4 is a left end view of the apparatus of FIG. 1 with certain partsbeing cut away.

FIG. 5 is an exploded perspective of a rotary bus bar joint and twoinduction coils with certain parts being cut away to illustrate portionsof the water cooling passages within the rotary joint

FIG. 6 is a diagram in perspective illustrating the route and directionof flow of cooling liquid through the left half of the bus bar, the busbar joint and the left induction coil.

FIG. 7 is an operational view in side elevation illustrating theinduction coils in solid lines in a member heating position within aninert atmosphere hood, and in an inoperative position in phantom lines.

FIG. 8 is an operational view in frontal elevation illustrating theinduction coils in member heating position, the inert atmospheric hoodbeing shown in phantom lines.

FIG. 9 is an operational view illustrating the two members weldedtogether with the inert atmospheric hood moved to the left with thepiston rod of a hydraulic cylinder.

FIG. 10 is a perspective in central section illustrating a pair ofinduction heating coils adapted to independently heat different sizemembers to an upsetting temperature and having laminations to aid theheating process.

FIG. 11 is a perspective similar to FIG. 10 but illustrating laminatedinduction coils for heating cylindrical members to upsettingtemperature.

FIG. 12 is a perspective similar to FIG. 10 but illustrating laminatedinduction coils for heating square or rectangular members to a bondingtemperature.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The induction welding apparatus 20 (FIGS. 1-4) of the present inventioncomprises a heavy frame 22 which supports an ajustable clampingmechanism 24 capable of rigidly supporting a first workpiece or memberM1, illustrated as a tube, which may vary in size between about 21/2inches to at least 6 inchyes in diameter. The member M1 is accuratelycentered on a fixed longitudinal axis A with a conventional chuck 26having movable jaws 28 that are simultaneously adjusted by a screwmechanism and wrench (not shown). The frame 22 also supports a hydrauliccylinder 30 having its longitudinal axis concentric with axis A. Thecylinder includes a piston rod 32 and a threaded extension 32' whichextends out of the left hand end (FIG. 2) of a cylinder case 34 and isoperatively connected to an adapter having a cavity 35 (FIGS. 8 and 9)to snugly receive one end of a second member M2 which is to be inductionwelded to the first member M1. The second member M2 is illustrated as ashort tube in all Figures except FIG. 1A which illustrates a male lugM2' that is induction welded to the first member M1; and a female lugM2", shown in phantom lines, connected to the male lug M2' by pin 36.FIG. 1A illustrates one use of the induction welding apparatus which isto weld long (20-40 foot) tubular members to male and female lugs forquickly, accurately and reliably manufacturing lattice booms for use oncranes or the like. An expandable plug 37 is inserted in the member M1and is expanded into sealing engagement in the member by compressed airfrom valve and conduit 37' to prevent air in the tube M1 from flowingaround the weldable surfaces S1,S2 (FIG. 8) during the heating andwelding operation.

The frame 22 also indirectly supports a rotary bus bar joint 38 (FIGS.1, 5 and 7) which includes two induction coils 40,42 which are movedbetween the ends of members M1,M2 (FIG. 8) when the weldable endsurfaces S1 and S2 of the two members are to be heated to an upsettingtemperature and are thereafter immediately rotated away from the membersM1,M2 as shown in FIG. 9 to allow the cylinder 30 to force the member M2into engagement with the member M1. The heating and upsetting operationstake place within an inert atmosphere hood 44 which is connected to thepiston rod 32 of the cylinder 30 as best shown in FIG. 2. A pair of heatstations containing transformers 46,48 (FIGS. 3 and 4) are also mountedon the frame 22 for horizontal adjustment. The transformer 46 providescurrent to the induction heating coils 40, while the transformer 48provides current to the coil 42.

More particularly, the frame 22 includes a plurality of heavytransversely extending I-beams 50 and a short longitudinally extendingI-beam 52 (FIGS. 1 and 4) that are supported on a concrete floor, whichbeams support a pair of longitudinally extending I-beams 54. Ahorizontal floor plate 56 is provided with a pluraltiy of tranversegrooves 58 therein. The I-beams and plate 56 are bolted together todefine a rigid base 60.

As best shown in FIG. 2, three thick transverse walls 62,64 and 66 arefitted into associated ones of the grooves 58; and also are fitted intogrooves 68,70 and 72, respectively, formed in a short cover plate 74.The floor plate 56 and cover plate 74 are connected to the walls 62,64and 66 by a plurality of capscrews (not shown). It will be noted thatthe wall 62 has a hole 76 (FIG. 1) therein for receiving member M1 andmay be secured to any of the four grooves 58 on the left portion of thefloor plate 56 if the member M1 is excessively long and requires thatthe clamping mechanism 24 be moved to the left. If the mechanism 24 ismoved to the left, a longer top plate is provided and is appropriatelygrooved for connection to the walls by capscrews.

The clamping mechanism 24 (FIGS. 1-4) includes a pair of spaced walls80,82 rigidly secured to a sturdy base 84 and a top wall 86 to which aplurality of hydraulic clamping cylinders 88 are secured. The cylinders88 each include a cylinder case 90 (FIGS. 1 and 4) and a piston rod 92.An upper V-block gripper head 94 is secured to each piston rod 92 andhas two gripper jaws 96 disposed at 90° to each other which cooperatewith a pair of lower gripper jaws 96 which are also disposed at 90° toeach other and are secured to a lower V-block gripper head 98 that isrigidly secured to the base 84. It is important that the jaws 94,96 bequite long (about 10 inches) as illustrated and be angled at 90° to eachother to preserve the ovality of the member M1, if the member is a tubeas illustrated, and also to firmly clamp the member M1 from movementwhen subjected to an upsetting force which may be as high as about236,00 pounds, depending upon the size of the members M1,M2 being weldedtogether. The clamping mechanism 24 and the strength of the apparatus 20is capable of upsetting metal having a weldable surface area of up toabout 30 square inches. The illustrated clamping mechanism is capable ofhandling members M1 up to 6 inches in diameter.

The clamping mechanism 24 (FIGS. 1-4) is adapted to be movedhorizontally, as previously mentioned, by mounting the wall 62 indifferent ones of the grooves 58 and providing a cover plate 74 ofappropriate length. The entire clamping mechanism 24 is also verticallyadjustable by means of a conventional right angle screw jack 100 whichis manually operated by a handwheel 102. The jack is mounted on asub-frame 104 (FIG. 4) having supporting bars 106 engaging flanges ofthe I-beams 54. Longitudinal movement of the clamping mechanism 24 todifferent position along the floor plate 56 is allowed after firstremoving the hand wheel 102 and its shaft 108.

In order to accommodate vertical movement of the clamping mechanism 24and yet maintain the mechanism firmly against the wall 62 during theupsetting operation, the wall 62 is provided with a pair of T-slots 110(FIG. 2) which slidable receive T-bars 112 therein. Each T-bar 112 isconnected to one end of a piston rod extension 114 of a hollow centerhydraulic cylinder 116. Each piston rod extension 114 extends through atube 118 which abuts the end walls 80,82. Each extension 114 is coupledto an associated piston rod 119 (FIG. 1) which extends through cylindercase 120 with a nut 122 on its protruding end. When it is desired toadjust the clamping mechanism 24 vertically, hydraulic pressure issupplied to the left end of each hydraulic cylinder case 120 thus movingthe piston rods 119 and extensions 114 to the right out of clampingengagement with the wall 62. When it is desired to firmly clamp themechamism 24 to the wall 62 hydraulic pressure is applied to the rightside of each cylinder 120 thus overcoming the substantial upsettingforce applied against the member M1 during the upsetting operation.Vertical keyway guides (not shown) may be formed in adjacent surfaces ofthe walls 62,82 to receive a key for accurately guiding the clampingmechanism when moved vertically.

The hydraulic cylinder 30 (FIGS. 1-3) has its cylinder case 34 mountedin a bore in the wall 66. A partially threaded extension 32' of thepiston rod 32 extends through a hole in the wall 64 which is countersunkto receive a stop ring 130 that acts as an abutment to be engaged by acalibrated adjustable stop 132 which limits the stroke of the piston rodextension 32' when moving in the upsetting direction which is to theleft in FIGS. 1-3. The ring 130 has two functions; the first function isto prevent accidental crushing of the fingers of an operator when thecalibrated ring 132 is moved into engagement with the ring 130, and thesecond function is to permit easy replacement of the ring 130 when thering is crushed by repeated impacts with the calibrated ring 132. Thecalibrated ring 132 is threaded on the piston rod and has calibrationmarks thereon which permit the upsetting stroke to be easily andaccurately adjusted in one thousands of an inch increments.

The left end (FIG. 2) of the piston rod extension is rigidly secured toa transducer 133 which is secured to a tool fixture platen 134 which hasa spacer box 136 bolted thereto. An inert atmosphere hood supportingblock 137 and an adapter 138 are releasably connected to the space box136. The adapter 138 is provided with the previously mentioned membersupporting cavity 35 (FIGS. 8 and 9) The cavity 35 is machined toconform to the external shape of the member M2 which is to be welded tothe member M1 as previously described. The adapter 138 is releasablyconnected to the member M2 by a set screw 140 as best shown in FIG. 8and may be removed and replaced by other adapters if a differentworkpiece, such as members M2' or M2" (FIG. 1A) are to be welded to themember M1.

The tool fixture platen 136 (FIGS. 1-3) is rigidly secured to four tierods 144 each of which extends through busings 146 fitted in the boresin the walls 64 and 66. Each tie rod 144 has a dust cap 147 closing thebores in the wall 66, and has a reduced diameter shouldered portion onthe other end which snugly fits within a bore in the tool platen 134. Asbest shown in FIG. 2, cap screws 150 are secured in threaded bores 152in the tie rods 144 thereby rigidly connecting the fixture platen 134 tothe tie rods 144.

As previously described, the pressure applying stroke of the piston rodextension 32' may be stopped by abutment between the ring 130 (FIG. 2)and the calibrated ring 132.

When welding a large plurality of indentical members together, such asmember M1 and M2 (FIGS. 8 and 9) the calibrated ring 132 may be screwedaway from the ring 130 so that the rings do no contact during thepressure upsetting operation. The required compressive force can bedetermined and set in a control circuit (not shown) connected to thetransducer 133 for providing the desired upsetting force on the ends ofthe members M1 and M2 without further operator assistance or the need ofa physical stroke limiting stop. Thus, the force transducer 133 isrelied upon to provide the proper welding pressure to assure that theheated ends of the members M1 and M2 are reliably welded together.

Although not illustrated, it will be understood that the cylinder 30 isconnected to a source of hydraulic fluid through conventional fastacting valving and a plurality of conventional hydraulic accumulatortanks which compress a gas above the hydraulic fluid for assuring rapidactuation of the ram in the upsetting direction.

As diagrammatically shown in FIGS. 1-3 and 7-9, an inert atmospherecontrol hood 44 is removably mounted on the hood supporting block 137. Asubstantially inert gas such as argon, helium, nitrogen or a mixture ofabout 95% argon and 5% hydrogen is directed past the weldable surfacesS1,S2 of the members M1 and M2 during the induction heating operationand the pressure upsetting or welding operation which occurs rapidlywithin a matter of seconds. The inert gas removes oxygen from thesurfaces to be welded thereby preventing poor welds due to oxidation andresulting scaling of the material from the surfaces being weldedtogether. The specific details and the manner of operation of the inertatmosphere control hood 44 are disclosed in the cross-referenced Brolinet al application Ser. No. 895,085 filed on Aug. 11, 1986 whichapplication is incorporated by reference herein. It will also beunderstood that the apparatus 20 is ideally suited for welding in anoxygen free atmosphere such as in outer space since the welding processis clean and spatter free.

The two transformers 46,48 (FIGS. 3 and 4), the rotary bus bar joint 38,and the induction coils 40,42 are adjustably supported on the frame 22by conventional lathe type way 162. The way 162 includes a carriage 164(FIG. 4) rigidly secured to the frame 22 and to a slide 165 upon whichthe transformers 46,48 and bus bars 166,166' (FIGS. 5 and 7) of therotary bus bar joint 38 are rigidly supported. The way 162 also includesa feed handwheel 170 (FIG. 3) and a screw mechanism (not shown) whichenables the operator to move the transformers 46,48 and induction coils40,42 longitudinally of the induction welding apparatus 20 to preciselycenter the induction coils 40,42 between the weldable surfaces S1,S2 ofthe members M1,M2 to be welded together. The transformers 46,48 arecapable of operating at 9,600 cycles per second but are preferablyoperated at about 6,000 cycles per second when welding steel tubestogether that are between about 204 inches in diameter. It will beunderstood that different materials may require different frequencies.

The rotary bus bar joint 38 is best illustrated in FIGS. 5 and 7 withthe flow of coolant through the bus bar joint being illustrated in FIG.6. Since the right half of the bus bar joint is a mirror image of theleft half, the left half will be described in detail while the righthalf will be identified by the same numerals followed by a prime (').

The bus bar joint 38 includes a left bus bar 166 which includes a pairof copper mounting blocks 182,184 that are rigidly secured to blocks185,186 of bus bars 187,188 of the transformer that are separated byinsulation 190. The right bus bar 166' is, of course, similarlyconnected to the right transformer 48.

The left bus bar 166 includes a pair of copper plates 192,194 brazed tothe associated mounted blocks 182,184, respectively. The copper platesand blocks 182,184 are separated by an insulation strip 196 all of whichhave a 90° bend therein. The insulation strip 196 projects between thecopper blocks 182,184 which are secured in clamping engagement with theinsulation strip 196 by insulated capscrews (not shown) connected to theinsulated wall 186 attached to the transformer 46. Thus, the two copperplates 192 and 194 define two spaced electrical conduits capable ofcarrying a very high current.

Two rectangular copper tubes 202,204 are brazed to the outer surfaces ofthe plate 192 and to the blcok 182 which have water passages therein fordirecting cooling fluid, preferably water, therethrough. Similar tubes(not shown) but similar to tubes 197',198' on the right bus bar 166' arebrazed to the outer surface of plate 194 and to the block 184 which haswater passages therein for cooling the plate 194.

The other ends of the copper plates 192,194 and copper tubes are brazedto associated copper blocks 212,214 which are connected to copper blocks216,218 by brass capscrews (not shown). The copper blocks 216,218 arebrazed to copper tongues 222,224 all of which are separated by aninsulation strip 225. The blocks and tongues form extensions of theplates 192,194 and are subject to frictional wear and preferably havetheir outer surfaces silver plated to reduce friction and to improveconductivity.

The copper blocks 182,184,212,214,216,218; and the four copper tubes202,204 (and the equivalents of right tubes 197', 198') have fluid flowpassages therein as best illustrated diagrammatically in the coolingconduit system 226 of FIG. 6. Inlet water enters the cooling conduitsystem through conduit 228, flows through passage 230 in the block 182,through the copper tubes 202,204 into blocks 212 and 216 and thencombine in a passageway 232 in blocks 216 and 212. A transverse passage234 in blocks 212,214 then causes the fluid to flow from block 212,through a passage in the insulation strip 196 and through passages inthe block 214, 218, and the outer tubes 197,198 connected to the copperplate 194 for return to the block 184 and discharged through a conduit236. The cooling water dissipates the heat formed in the bus bar 166 toa temperature that is low enough to prevent burns if touched by theoperator.

In order to transmit electrical current and cooling water to theinduction coil 40, and to change the input and output current pathsleading to the coil 40 from separated vertical paths to separatedhorizontal paths, a rotatable arm 240 is formed from two copper sections242 and 244.

The arm section 242 is non-linear in order to rotatably sandwich thetongue 222,224 between arm sections 242 and 244. The arm section 242includes a rectangular copper cooling tube 246 with the arm section andtube brazed to each other and to a lower copper block 248 having waterpassages 250,252 (FIGS. 5 and 6) therein with the passages 252communicating with an inlet water hose 254.

The arm section 244 is a linear section which includes a copper coolanttube 254 and an upper copper block 258 having coolant passages 260,262communicating with opposite ends of the tube 256. The arm section 244copper tube 256 and the upper block 258 are brazed together. A verticalelectrical insulation strip 266 is disposed between the outer ends ofthe arm sections 242,244; and a horizontal insulation strip 268 isdisposed between the lower block 248 and upper block 258 to electricallyinsulate the two arm sections and blocks from each other. The surfacesof the arm sections 242,244 which rotatably contact the surfaces of thetongues 222,224 are preferably silver plated to minimize frictional wearand to increase and improve conductivity.

In order to rotatably connect the left arm 240 to the tongues 222,224;and to connect the equivalent right arm 240' to the tongues 222' and224'; an induction coil mounting blade 269 and pivot shaft 270 arerigidly connected together and are constructed from a non-metallicmaterial. One side of the shaft 270 rotatably extends through a flangedand threaded tubular bushing 271. The bushing has an adjustment nut 272screwed thereon which bears against the resilient O-ring 273 ofnon-conductive material which may be compressed a sufficient amount toestablish good electrical contact between the tongues 222,224 and theassociated arm sections 242,244. The ends of the pivot shaft 270 extendsthrough holes 274,274' in lever arms 276,276' and are rigidly connectedthereto by set screws 278,278'. The lever arms 276,276' are securelyconnected to the rotatable arms 240,240' and to the coil mounting blade269, by non-conductive bolts 278 which extend through the holes in thelever arms 276,276', through the holes in the lower blocks 248,248' andupper blocks 258,258', and through holes in the coil mounting blade 269.

The left coil 40 is formed from copper tubing which is shaped to conformto the shape and size of the weldable surface S1 (FIG. 8) to be heatedto an upsetting temperature. One end of the coil is brazed to an uppertube 282 which has its other end welded to an upper mounting block 284having a flow passage 286 therein that communicates with the passage 262in the upper block 258 when the block 258 and 284 are bolted together.Similarly, a lower copper tube 288 is brazed to the other end of thecoil 40 and to a lower copper block 290 which is bolted to the lowercopper block 248. The coolant flow passage 250 in block 248 communicateswith a flow passage 292 in block 290. Thus, coolant flows from inlethose 254 through conduits in the direction indicated in FIG. 6. Moreparticularly, the coolant flows from hose 254, through lower conduit252, through copper tube 246 into passage 250 in lower block 248,through a passage 292 in block 290, through the lower copper tube 288,through the coil 40, through the upper tube 282, through the passage 286in the upper block 284 and into passage 262 in the upper block 258 whichthen flows through copper tube 256 and passage 260 in the upper block258 and is discharged through a hose 293.

It will be noted that the ends of the coils 40,42; upper tubing 282 andlower copper tubing 288, upper block 284 and lower block 248 areelectrically insulated from each other by an insulation strip 294. Thesecomponents are also insulated from each other by one or more verticalinsulation strips 296. In order to firmly support the coils 40,42, anglebars 298,298' are welded to the lever arms 276,276' and project belowthe induction coils. A non-metallic insulation plate 299 is bolted tothe bars 298,298' and provide support for the lower surfaces of thecopper tubes 288,288' that are connected to the coils 40,42.

A fast acting air cylinder 300 (FIGS. 4, 5 and 7) has a piston rod 302pivotally connected to a rod 304 secured to the lever arms 276,276'; andhas its case end pivotally connected to a bracket 308 (FIG. 4) that issecured to the previously described longitudinally movable slide 165that permits coils 40,42 to be moved to different positionslongitudinally of the induction welding apparatus 20.

FIG. 10 illustrates members M1a and M2a having weldable surfaces S1a andS2a of different cross-sectional areas. In order to simultaneously raiseboth surfaces S1a and S2a to their upsetting temperatures, a large coil40a is disposed adjacent the large surface S1a while a smaller coil 42ais disposed adjacent the surface S2a. In order to more effectivelyconcentrate the induced heat into the surfaces S1a and S2a, both coils40a and 42a have U-shaped laminations 310,312 formed thereon, whichlaminations 310,312 are preferably constructed of silicon iron of about0.007 inches thick and control ver high magnetic fields. A non-metallicinsulating disc 314 is disposed between the two coils 40a,42a.

A pair of sensors, preferably optical temperature sensors 316,318 suchas infrared pyrometers, are provided to detect the temperature of thesurfaces S1a and S2a. The amount of current directed to the coils40a,42a or the length of time the current is applied, or both, may bevaried so that both surfaces S1a, and S2a are raised to the upsettingtemperature at the same time. The cross-referenced Brolin et al U.S.application Ser. No. 896,904 filed on Aug. 11, 1986 discloses and claimsthe preferred circuitry for controlling the heat applied to the surfaceS1a and S2a along with the controlling of many other functions of theapparatus.

FIG. 11 discloses a pair of induction coils 40b and 42b adapted to heatthe end surfaces S1b and S2b of solid cylindrical members M1b and M2b toupsetting temperatures. The end surfaces of the members are drilled toprovide short holes 318,320 therein which received some of the upsetmaterial during the pressure applying upsetting operation.

FIG. 12 discloses a pair of substantially square induction coils 40c and42c adapted to heat the end surfaces S1c and S2c of square orrectangular members M1c and M2c to upsetting temperature.

In operation of the induction welding apparatus 20 (FIGS. 1-4) of thepresent invention, the operator first determines the type of members M1and M2 to be induction heated and pressure welded together. If themembers are of relatively small diameter tubular construction such as21/2 inch outside diameter tubes having wall thicknesses of about 0.2inch, are of the same material and having weldable surfaces S1, S2 ofthe same size, the operator may select a single coil such as coil 40along with certain cooling passages to simultaneously heat both surfacesS1 and S2 of the members M1 and M2 to be welded together.

Assume, however, that the operator selects the two coils 40,42 (FIGS.1-4 and 5) to weld members M1,M2 together. The operator then sets up themachine by first mounting the two coils to the blocks 248,258 and248',258' as shown in FIG. 5. The operator then positions member M2 inthe cavity 35 (FIG. 8) of the adapter 138 with the piston rod 32 of theram 30 fully retracted. The operator then operates the handwheel 170(FIG. 3) to adjust the two transformers 46,48 and the coils 40,42longitudinally of the apparatus 20 to an induction heating positionwherein a small air gap is disposed between the weldable surface S2 ofthe member M2 and the adjacent face of the coil 42. The operator thenplaces the member M1 in the chuck 26 and in the clamping mechanism 24and clamps the member M1 between the jaws 28 of the chuck manually; andthereafter hydraulically closes jaws 96 by actuating the hydraulicclamping cylinders 88 with the weldable surface S1 of member M1 beingspaced from the adjacent surface of the coil 40 by a small air gap whenthe coils 40,42 are in their heating position illustrated in FIG. 8.With the member M1 clamped in the clamping mechanism 24, the operatordetermines if the longitudinal axis of the member M1 coincides with thelongitudinal axis of the member M2. If the axes of the members do notcoincide, the operator actuates cylinders 116 to move the piston rods119 and their extensions 114 to the right (FIGS. 1 and 2) and thenoperates the handwheel 102 to raise or lower the member M1 until it isproperly aligned in welding position with the member M2. The operatorthen actuates a conventional valve to cause cylinders 116 to move thepiston rods and rod extensions 114 to the left (FIGS. 1 and 2) therebyfirmly clamping the clamped mechanism 24 against the wall 62 and themember M1 between the jaws 94,98.

If the member M1 is tubular and the end portions of the tube adjacentthe surface S1 is not sealed by another means, an expandable plug 37(FIG. 1A) is expanded by air pressure from air conduit and valve 37' toprevent air from flowing around the weldable surfaces S1,S2 during theinduction heating and pressure upsetting operations.

After the members M1 and M2 have been mounted as above described, theinert atmosphere hood 44 (FIGS. 1-3 and 7-9) is mounted on the hoodsupporting block 137 in the induction heating position as shown inphantom lines in FIG. 8 and in the upsetting position as shown in FIG.9. The hood 44 and its manner of opration is fully disclosed and claimedin the cross-referenced Brolin et al U.S. application Ser. No. 895,085filed on Aug. 11, 1986.

Briefly, the hood 44 is manually mounted about and sealed to the outersurfaces of the members M1 and M2 and includes an upper portionremovably connected to a lower portion so that both portions may beremoved from the members when welded together. When in operativeposition a substantially inert gas such as argon, helium, nitrogen or a95% mixture of argon and hydrogen are directed past the weldablesurfaces S1,S2 in a laminar flow which purges air from the surfacesS1,S2 and discharges it through diffusers or pads, which are preferablyformed of vinyl or urethane foam, in the lower end of the hood. The foampads are split to permit the coils 40,42 to move into and out of thehood.

After the induction heating pressure welding apparatus 20 has been setup as above described, the operator actuates control circuits which aredisclosed and described in the cross reference Brolin et al U.S.application Ser. No. 896,904 filed on Aug. 11, 1986 to place the machinein operation.

With the inert gas flowing past the surfaces S1 and S2, and with the twocoils raised to operative position shown in FIG. 8, an oxygen detectorsenses the gas in the hood 44 and energizes the induction coils when thedetector detects an insufficient amount of oxygen in the hood toadversely affect the weld. The control circuit maintains the inductioncoils energized until temperature sensing means in the control circuitindicate that the weldable surfaces S1,S2 have been raised to theupsetting temperature at which time the circuit first actuates the aircylinder 300 to move the induction coils 40,42 from between the membersM1,M2 and then actuates the hydraulic cylinder 30 thereby forcing memberM2 against member M1 with suffieient force to upset the heated materialadjacent the weldable surfaces S1,S2 as shown in FIG. 9 thus completingthe weld. The induction heating and pressure welding steps require aboutfive seconds. During this time the coolant, preferably water, isdirected through the bus bar and induction coil assembly as shown inFIGS. 5 and 6 to cool the assembly. It will be understood that thecopper tubing 246,256 and 246',256' (FIG. 5) cool the surfaces of therotary joint.

After the weld has been completed the set screw 140 (FIG. 8) is releasedfrom member M2, the cylinder 30 retracts the box 136 and block 137 (FIG.9) away from member M2, is retracted to the FIG. 8 position, the gassupply to the hood 44 is turned off and the hood is separated andremoved from the apparatus 20. The welded members M1,M2 are thenunclamped from the chuck 26 and the clamping mechanism 24 and areremoved from the apparatus 20 thus completing one cycle of operation.Other cylces of operation on the same type members may take placewithout again setting up the machine except for positioning the membersM1 and M2 in welding position and clamping the member M1 in the heatingposition. Also, hood 44 is remounted around the members M1 and M2 andsecured to the hood supporting member 137.

If tubular members M1a and M2a (FIG. 10) having different weldablesurface areas are to be welded together, the induction coils 40a, 42aare substituted for the coils 40,42 and the operation is repeated.

If metals of different types, for example, steel to cast iron or brassto copper are to be welded together, laminated induction coils of thesame size or different sizes similar to the coils 40a and 42a may beused and be simultaneously raised to the required upsettingtemperatures.

Similarly, the FIG. 11 induction heads 40b and 42b may be substitutedfor the heads 40 and 42 when solid metal rods 41b and 42b are to bewelded together. Likewise, induction coils of different shapes and sizessuch as the induction coils 40c and 42c (FIG. 12) may be used to weldmembers of different sizes, shapes, and metals together followingsubstantially the same steps as described above in regard to weldingmembers M1 and M2 together.

From the foregoing description it is apparent that the induction heatingand pressure welding apparatus of the present invention is capable ofwelding metals of different sizes and shapes and of different typestogether while in a substantially inert atmosphere by separately heatingthe weldable surfaces of two members by independently controlledinduction coils. Immediately thereafter, the two members are pressedtogether with sufficient force to upset the weldable surfaces thuswelding the two members together. The apparatus is capable of beingmanually operated, but is preferably operated in a semi-automatic mannerto provide consistently good welds when making a plurality of identicalwelded parts.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

What is claimed is:
 1. In an induction heating pressure weldingapparatus, a rotary bus bar joint comprising:a two piece conductive busbar including a tongue operatively connected to a source of highfrequency current; first insulator means for electrically insulating onepiece of said bus bar from the other piece; a two piece conductive armmounted on said two piece bus bar for arcuate movement about an axiswith said arm pieces being electrically connected to associated bus barpieces; second insulator means for electrically insulating one piece ofsaid arm from the other piece; an induction coil conforming to the shapeof the weldable surfaces to be welded together and having two ends;means electrically connecting one end of said coil to one piece of saidarm and electrically connecting the other end of said coil to said otherpiece of said arm; third insulating means for electrically insulatingthe ends of said coil and said electrical connecting means from eachother; means for pivoting said arm and said coil about said axis; andmeans for cooling said bus bar, said tongue, said arm, said coil andsaid connecting means.
 2. An apparatus according to claim 1 wherein saidfirst and second insulating means are disposed normal to each other forchanging the flow of said high frequency current between generallyvertical paths and generally horizontal paths.
 3. An apparatus accordingto claim 2 wherein said bus bars, tongues and arms include conductiveplates that are narrow horizontally and wide vertically, and whereinsaid coil and said connecting means are wide horizontally and narrowvertically for heating weldable surfaces that are disposed vertically onhorizontally disposed members.
 4. An apparatus according to claim 1 andadditionally comprising means defining coolant passages in said twopiece bus bar, said two piece arm, said connecting means and said coil;and means for directing a coolant through said coolant passages.
 5. Anapparatus according to claim 1 wherein said bus bars, tongues and armsinclude conductive plates that are narrow in a first direction and widein a second direction, and wherein said coil and said connecting meansare wide in said first direction and narrow in said second direction forheating weldable surfaces that are disposed in said second direction onmembers elongated in said first direction.
 6. In an induction heatingpressure welding apparatus, a rotary bus bar joint comprising;a twopiece electrically conductive bus bar operatively connected to a sourceof high frequency current; a two piece electrically conductive tongueprojecting from one end of said bus bar and having a first holes thereindefining a pivot axis; first electrical insulating means disposedbetween said two pieces of said bus bar and said tongue for providingtwo separate circuits, said electrical insulating means in said tonguelying in a predetermined plane; a two piece electrically conductive armhaving second pivot holes in one end portion and each arm having aseparate mounting block on the other end portion; tubular connectingmeans of non-conductive material inserted through said first and secondholes for pivotally connecting said two piece arm in electricalconductive engagement with said two piece tongue; second electricalinsulating means disposed in a plane normal to the plane of said firstinsulating means for electrically separating said two pieces of said armfrom each other for providing two separate electrical circuits; atubular electrically conductive induction coil shaped to conform to theshape of the weldable surfaces of two members to be welded together andhaving spaced end portions; a first electrically conductive connectingmeans connecting one end portion of said coil to one of said blocks; asecond electrically conductive connecting means connecting the other endportion of said coil to the other block; a mounting blade ofnon-conductive material connected to said two piece arm; meansoperatively connected to said arm for moving said two piece arm and coilin an arcuate path around said pivot axis; and means for cooling saidbus bar, said tongue, said arms, said conducting means and said coil. 7.An apparatus for induction heating and pressure welding weldablesurfaces of two members together comprising:a frame; a hydrauliccylinder secured to said frame and having a piston rod adapted tosupport a first member and being movable between a surface heatingposition and a surface upsetting position; clamping means secured tosaid frame and adapted to securely clamp second member in fixed positionwith a weldable surface disposed in alignment with the weldable surfaceof said first member; hood means for directing a laminar flow ofsubstantially inert gas past said weldable surfaces for purging air fromsaid surfaces; means defining an induction heating coil movable betweena first position disposed between and spaced a short distance from saidsurfaces for heating said surfaces to an upsetting temperature, and asecond positon out of alignment with said weldable surfaces for allowingsaid hydraulic cylinder to immediately thereafter force said firstmember against said second member with sufficient force to upset saidheated surfaces and weld said two surfaces together, means for directinga high frequency current through said coil when in said first positionto heat said surfaces to an upsetting temperature; said clamping meansincluding a bodily adjustable sub-frame movable supported by said frame,a first V-block gripper head rigid with said sub-frame, a second V-blockgripper head carried by said sub-frame and movable relative to saidfirst V-block gripper head for clamping said second member therebetween,and adjustment means for moving said sub-frame between a positionwherein said weldable surfaces of said first and second members are outof alignment with each other to a position wherein said surfaces are inweldable alignment with each other; said sub-frame abutting a portion ofsaid frame having T-slots therein, a plurality of hydraulic cylinderssecured to said sub-frame, a piston rod in each cylinder, a T-baroperatively connected to each piston rod and slidably received in saidT-slots, when said sub-frame is in locked position, each position rodbeing retracted to rigidly connect said sub-frame to said frame. whensaid sub-frame is to be adjusted each piston rod being moved to permitsliding movement of said T-bars in said slides.
 8. An apparatus forinduction heating and pressure welding weldable surfaces of two memberstogether comprising:a frame, a hydraulic cylinder secured to said frameand having a piston rod adapted to support a first member and beingmovable between a surface heating position and a surface upsettingposition; clamping means secured to said frame and adapted to securelyclamp second member in fixed position with a weldable surface disposedin alignment with the weldable surface of said first member; hood meansfor directing a laminar flow of substantially inert gas past saidweldable surfaces for purging air from said surfaces; means defining aninduction heating coil movable between a first position disposed betweenand spaced a short distance from said surfaces for heating said surfacesto an upsetting temperature, and as second position out of alignmentwith said weldable surfaces for allowing said hydraulic cylinder toimmediately thereafter force said first member against said secondmember with sufficient force to upset said heated surfaces and weld saidtwo surfaces together, means for directing a high frequency currentthrough said coil when in said first position to heat said surfaces toan upsetting temperture; said hood means inlcuding open cell foam rubberpads therein for allowing said induction heating coil to be moved intosaid hood between said weldable surfaces and out of said hood and formaintaining a substantially inert atmosphere around said weldablesurfaces which is at a higher pressure than the pressure externally ofsaid hood and progressively decreases in pressure from one end to theother end of said hood.
 9. An apparatus according to claim 8 andadditionally comprising means for operatively connecting said hood tosaid piston rod when said surfaces are being heated to an upsettingtemperture and when said heated surfaces are being upset.
 10. Anapparatus for induction heating pressure welding two weldable surfacesof two members together, comprising:means defining at least oneinduction coil; pressure applying means for moving at least one of themembers along a presure applying path; means for supporting the twomembers with said weldable surfaces spaced from each other; means forproviding a laminar flow of a substantially inert gas around saidweldable surfaces; means for establishing relative movement between saidmembers and said induction coil for first positioning the coil in closeproximity between said weldable surfaces and for thereafter spacing saidcoil from the pressure applying path of movement of said weldablesurfaces; means for directing a high frequency current through said coilwhen positioned between said weldable surfaces to heat said surfaces toan upsetting temperature; means for forcing said weldable surfacestogether with sufficient force to upset said heated surfaces for weldingsaid surfaces together when said coil is spaced from said surfaces; saidcoil means having opposed heating surfaces disposed between weldablesurfaces of different areas, and means for positioning one of saidheating surfaces of said coil means closer to the weldable surfacehaving the larger area with the other heating surface being spaced alesser distance from the smaller weldable surface for controlling thetemperature rise in each weldable surface for substantiallysimultaneously raising both weldable surfaces to the upsettingtemperature.
 11. A method of induction heating pressure welding weldablesurfaces of two members together using at least one induction coil andpressure applying means for moving at least one of the members along apressure applying path comprising the steps of:supporting the twomembers with said weldable surfaces spaced from each other; providing alaminar flow of a substantially inert gas around said weldable surfaces;establishing relative movement between said members and said inductioncoil for first positioning the coil in close prosimity between saidweldable surfaces and for thereafter spacing said coil from saidpressure applying path of movement of said weldable surfaces; directinga high frequency current through said coil when between said weldablesurfaces to heat said surfaces to an upsetting temperature; forcing saidweldable surfaces together with sufficient force to upset said heatedsurfaces for welding said surfaces together when said coil is spacedfrom said surfaces; and wherein the weldable surfaces are of differentareas, and wherein the coil has opposied heating surfaces disposedbetween the weldable surfaces of different area; and including the stepof positioning one of said opposed heating surfaces of said coil closerto the weldable surface having a larger area than the surface having asmaller area for controlling the temperature rise in each weldablesurface for substantially simultaneously raising both weldable surfacesto the upsetting temperture.